Organic compounds in aqueous solution

The role of the pH of the medium in the electrode reactions of organic compounds in aqueous solutions is well understood and has been recently reviewed in detail (Zuman, 1969). In particular, our understanding of this parameter is due to the large number of polarographic investigations where it has been found that the half-wave potential, the limiting current and the shape of the wave for an oxidation or reduction process may all be dependent on the acidity of the medium. 

Anbar, M. and Neta, P. (1967). A compilation of specific biomolecular rate constants for the reaction of hydrated electrons, hydrogen atoms and hydroxyl radicals with inorganic and organic compounds in aqueous solutions. Int. J. Appl. Radiat. Isot. 18, 493-497. 

The processes associated with the photomineralisation of a wide range of organic compounds in aqueous solution using Ti02 are shown in Figure 11.11, where ... 

Ultrasonic irradiation has also been employed for chemical remediation of water but the mode of sonochemical degradation of organic compounds in aqueous solution depends upon their physical and chemical properties. This is because there are two ways in which the cavitation bubble can function. In the case of volatile chemicals which enter the bubble, destruction occurs through the extreme conditions generated on collapse. In the case of chemicals remaining in the aqueous phase the bubble acts as a source of radicals (H, HO and HOO ) which enter the bulk solution and react with pollutants. 

Effects of electrolytes on the solubility of organic compounds in aqueous solutions were established empirically more than 100 years ago by Setschenow (1889). He found that the presence of dissolved inorganic salts in an aqueous solution decreases the aqueous solubility of nonpolar and weak polar organic compounds. This effect, known as the salting-out effect, is expressed by the empirical Setschenow formula... 

How may an OH-group influence the behavior of an organic compound in aqueous solution ... 

Molecular Interpretation of the Excess Free Energy of Organic Compounds in Aqueous Solutions... 

Before we deal with these molecular aspects in detail, it is instructive to inspect the enthalpic () and entropic (-T Sj,j,) contributions to the excess free energies of various organic compounds in aqueous solution (Table 5.3). Values representative of saturated aqueous solutions of the compounds have been derived from measurements of the enthalpies of dissolution of the liquids (i.e., = AwJ //, Fig. 5.1) or solids (// ... 

In summary, we can conclude that the excess free energy of an organic compound in aqueous solution, and thus its activity coefficient, depends especially on (1) the size and the shape of the molecule, and (2) its H-donor and/or H-acceptor properties. 

Mitchell, B. E., and P. C. Jurs, Prediction of infinite dilution activity coefficients of organic compounds in aqueous solution from molecular structure , J. Chem. Inf. Comput. Sci., 38, 200-209 (1998). 

Neta P (1972) Reactions of hydrogen atoms in aqueous solutions. Chem Rev 72 533-543 Neta P, Schuler RH (1972) Rate constants for reaction of hydrogen atoms with aromatic and heterocyclic compounds. The electrophilic nature of hydrogen atoms. J Am Chem Soc 95 1056-1059 Neta P, Fessenden RW, Schuler RH (1971) An electron spin resonance study of the rate constants for reaction of hydroqen atoms with organic compounds in aqueous solutions. J Phys Chem 75 1654-1666... 

H. Okuno, B. Yim, Y. Mizukoshi, Y. Nagata and Y. Maeda, Sonolytic degradation of hazardous organic compounds in aqueous solution, Ultrason. Sonochem., 7 (2000) 261-264. 

The discovery of hydrated electrons in the radiolysis of water is undoubtedly one of the outstanding events in chemistry in this decade. Hydrated electrons have been found to react with many organic compounds in aqueous solution, and the kinetics of the reactions have been measured. From these kinetic studies, as well as from the detection of intermediates and the identification of final products, sufficient information has accumulated to allow a comprehensive discussion of the mechanisms of these reactions. 

The great effort invested in the investigation of the radioly tic behaviour of organic compounds in aqueous solutions has been justified by the assumption that the major part of the radiobiological damage to the living cell at the molecular level may be described by the radiolytic behaviour of organic solutes in aqueous solution. Ultimately, this effort led to the discovery of the hydrated electron and its reactions. 

Koester R, Asmus K-D. Pulse radiolysis studies of halogenated organic compounds in aqueous solution. Proceedings of 3rd Tihany Symposium on Radiation Chemistry, Budapest, 1972, 1095-1106. 

Another limiting factor is that it may not be possible to use some of these electronically conducting organic compounds in aqueous solutions. This is true of the polymer most used in new polymer batteries, polyacetylene, for which an appropriate solvent is propylene carbonate (see Fig. 4.115). 

WoRNER M, Schnabel C, Hashem TM, Ze-GENHAGEN F, GlESER J, BrAUN AM (1998) Dehalogenation of Halogenated Organic Compounds in Aqueous Solution by Different Photochemical Methods, J. Inf. Recording 24 455-460. 

TABLE 8 Cyclovoltammelric Study Results of Selected Organic Compounds in Aqueous Solution (pH = 7. All Potentials Reported vs. SCE)... 

Traube, J. [I.] Ueber die Capillaritatsconstanten organischer Stoffe in wasserigen Losungen. [On the capillary constants of organic compounds in aqueous solutions.] Justus Liebigs Annalen der Chemie 265, 27-55 (1891). 

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